Get-msoluser :The socket connection was aborted

Some things to consider:

1. Are you running through proxy - this can lead to some timeout issues
2. Ensure you are running the latest Microsoft Azure Active Directory Module for Windows PowerShell
3. Move to the newer Azure Active Directory V2 PowerShell module instead of this module

If you choose option 3, the equivlant starting point would be:

Get-AzureADUser -top 10000 | select displayname | measure-object

Or get ALL:

 Get-AzureADUser -all $true | select displayname | measure-object